Lung neutrophils on a paleo diet: lean, mean inflammatory machines

Sites of acute inflammation become austere environments for the procurement of energy. The combination of oxygen depletion (hypoxia) and decreased glucose availability requires surprising metabolic adaptability. In this issue of the JCI, Watts et al. examined the metabolic adaptability of murine neutrophils to the setting of acute pulmonary inflammation elicited by exposure to nebulized endotoxin. While neutrophils are generally considered a primarily glycolytic cell type, Watts et al. used a combination of labeled amino acids and high-resolution proteomics to reveal that the harsh environment of the inflammatory lesion drives neutrophils toward de novo protein synthesis and extracellular protein scavenging as a primary fuel. This study provides compelling evidence that tissue neutrophils scavenge extracellular proteins to fuel carbon metabolism, which aids in de novo protein synthesis and the promotion of an inflammatory phenotype. These observations reveal the surprisingly creative extent to which cells and tissues might adapt to energy-deficient inflammatory environments.